This invention relates to an improved washer and aspirator device having improved tips, associated tip seals, reaction well seals and a frame. More particularly, this invention relates to an improved hand-held washer and aspirator device which is utilized in washing beads in reaction wells of diagnostic immunoassays.
Standard diagnostic immunoassays such as AUSRIA.RTM. hepatitis radioimmunoassay and AUSZYME.RTM. hepatitis enzyme immunoassay manufactured by Abbott Laboratories, North Chicago, Ill., contain a solid phase reagent such as a spherical polystyrene bead having an antigen or antibody coated thereon. This bead reagent is placed in a reaction well and is contacted with a human biological specimen such as a serum or urine suspected of containing an antigen or antibody to be detected in the immunoassay. After an incubation period, the human biological sample is separated from the bead by washing the bead and the reaction well, and then the wash solution and human biological sample are aspirated from the well. Next, a liquid reagent such as an antigen or antibody linked to an enzyme or radioisotopic label is added to the bead. These reagents are incubated, and then the solid phase is again washed and aspirated as described above to remove any unbound liquid reagent.
U.S. Pat. No. 3,949,771 describes a washer and aspirator device which delivers and removes wash solutions in assays such as those described above. These prior art washer and aspirator devices require careful manipulation including raising and lowering of the device in the reaction wells in precise timing with delivery and removal of wash solution to avoid splashing and incomplete washing of reaction wells. If, for example, the liquid reagent is inadvertently deposited at the top of the reaction well, it is difficult to remove this reagent using the prior art devices, and this extraneous liquid reagent will later interfere with assay results.
In particular, since enzyme immunoassays have gained increasing popularity over radioimmunoassays due to the lack of radioactive waste, the need for a less technique dependent method for washing beads in reaction wells has surfaced. A much smaller amount of extraneous liquid reagent in enzyme immunoassays may interfere with assay results as compared to radioimmunoassays.